With equipment designed to work in many parts of the world there is often a problem of matching available power and particularly voltage levels to equipment needs. Thus in some instances 115 volts AC is the standard available voltage while in other locations 230 volts AC is the standard available voltage. Many pieces of equipment address the problem by having the capacity to operate with different voltages but require electrical jumper wires to be manually positioned in accordance with the available voltage.
Another approach to connecting either of two voltages to a load is to provide two equipment electrical plugs, one having prongs configured to plug into 115 volt outlet and one having prongs configured to plug into a 230 volt outlet. One of the two plugs is electrically connected directly to the equipment while the other is connected to an auto transformer or similar device to alter the input voltage to the other of the two voltages. The output of the auto-transformer is then connected to the equipment which is therefore configured to operate at only one of the two possible input voltages.
The prior art approach of positioning jumper wires is subject to operator error in that if 230 volts is supplied and the equipment is configured to operate at 115 volts considerable damage can result. With the second approach, the autotransformer is of considerable weight, cost and size, and produces considerable heat which must be disapated by the equipment. Also with readily available plug adaptors it is still possible to insert the wrong plug into the wrong voltage outlet supply resulting in inoperative equipment or damage to the equipment.